Interesting proposal, but with severe risks: becoming dependent on a single specific compiler and rustc could include malicious code that isn’t obvious to an outside auditor. See https://aeb.win.tue.nl/linux/hh/thompson/trust.html Ken Thompson demonstrated this.
But what will the future of RustPython be? https://github.com/RustPython/RustPython/
Major shifts like this are complex, not so only from a technical perspective but even more because a lot of humans with different opinions are involved. But radical changes are sometimes needed to be innovative again.